U.S. patent application number 16/160136 was filed with the patent office on 2019-04-25 for traffic light information providing system and traffic light information providing method, and server used therefor.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Hideo HASEGAWA, Munehiro KAMIYA, Shinji KURACHI, Satoru SAKUMA, Tomoya SHIMIZU, Shuhei YAMAMOTO.
Application Number | 20190122548 16/160136 |
Document ID | / |
Family ID | 66169452 |
Filed Date | 2019-04-25 |
United States Patent
Application |
20190122548 |
Kind Code |
A1 |
SAKUMA; Satoru ; et
al. |
April 25, 2019 |
Traffic Light Information Providing System and Traffic Light
Information Providing Method, and Server Used Therefor
Abstract
A traffic light information providing system includes a vehicle
and a server configured to communicate with the vehicle, and
provides information on change in color of a traffic light to the
vehicle. The vehicle transmits to the server, vehicle data
including time information and position information of the vehicle
at the time when the vehicle resumes running from a state of stop
at an intersection. The server operates and stores a period of
change from the red light to the green light of a traffic light
provided at the intersection based on the vehicle data. The server
transmits information indicating timing of change to the green
light of the traffic light based on the stored period of change, to
a vehicle which approaches the intersection.
Inventors: |
SAKUMA; Satoru;
(Nagakute-shi, JP) ; YAMAMOTO; Shuhei; (Aichi-ken,
JP) ; KAMIYA; Munehiro; (Anjo-shi, JP) ;
HASEGAWA; Hideo; (Nagoya-shi, JP) ; KURACHI;
Shinji; (Nagoya-shi, JP) ; SHIMIZU; Tomoya;
(Nagoya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota-shi |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
66169452 |
Appl. No.: |
16/160136 |
Filed: |
October 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G08G 1/0145 20130101;
G08G 1/096 20130101; G08G 1/096716 20130101; G08G 1/096775
20130101; G08G 1/0133 20130101; G08G 1/095 20130101; G08G 1/096741
20130101; G08G 1/08 20130101; G08G 1/0112 20130101; G08G 1/07
20130101 |
International
Class: |
G08G 1/096 20060101
G08G001/096; G08G 1/01 20060101 G08G001/01; G08G 1/08 20060101
G08G001/08; G08G 1/095 20060101 G08G001/095 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2017 |
JP |
2017-202799 |
Claims
1. A traffic light information providing system for providing
information on change in color of a traffic light to a vehicle, the
traffic light information providing system comprising: a vehicle;
and a server configured to communicate with the vehicle, the
vehicle being configured to transmit to the server, vehicle data
including time information and position information of the vehicle
when the vehicle resumes running from a state of stop at an
intersection, the server being configured to operate and store a
period of change from a red light to a green light of a traffic
light provided at the intersection based on the vehicle data, and
transmit information indicating timing of change of the traffic
light to the green light based on the stored period of change to a
vehicle which approaches the intersection.
2. The traffic light information providing system according to
claim 1, wherein the vehicle is configured to transmit the vehicle
data to the server when a vehicle speed exceeds a threshold value
from the state of stop at the red light at the intersection.
3. The traffic light information providing system according to
claim 1, wherein the vehicle is configured to transmit the vehicle
data to the server when the vehicle resumes running from a state
that the vehicle is at a head of vehicles which stop at the
intersection.
4. The traffic light information providing system according to
claim 1, wherein the server is configured to identify the traffic
light based on the position information and to operate the period
of change of the traffic light based on the time information
accumulated for each identified traffic light.
5. The traffic light information providing system according to
claim 4, wherein the server is configured to operate a predicted
time of change to the green light of the traffic light based on
latest time information on change to the green light of the traffic
light and the operated period of change, and to transmit the
predicted time to the vehicle which approaches the
intersection.
6. The traffic light information providing system according to
claim 4, wherein the server is configured to operate and store the
period of change of the identified traffic light in accordance with
at least any one category of a month, a day of a week, and a time
of a day.
7. A traffic light information providing method of providing
information on change in color of a traffic light in a system
comprising a vehicle and a server configured to communicate with
the vehicle, the traffic light information providing method
comprising: transmitting to the server, vehicle data including time
information and position information of the vehicle when the
vehicle resumes running from a state of stop at an intersection;
operating and storing a period of change from a red light to a
green light of a traffic light provided at the intersection based
on the vehicle data; and transmitting information indicating timing
of change of the traffic light to the green light based on the
stored period of change, to a vehicle which approaches the
intersection.
8. A server included in a traffic light information providing
system for providing information on change in color of a traffic
light to a vehicle, the server being configured to communicate with
the vehicle, and the server being configured to receive vehicle
data including time information and position information of the
vehicle when the vehicle resumes running from a state of stop at an
intersection, operate and store a period of change from a red light
to a green light of a traffic light provided at the intersection
based on the vehicle data, and transmit information indicating
timing of change of the traffic light to the green light based on
the stored period of change, to a vehicle which approaches the
intersection.
Description
[0001] This nonprovisional application is based on Japanese Patent
Application No. 2017-202799 filed with the Japan Patent Office on
Oct. 19, 2017, the entire contents of which are hereby incorporated
by reference.
BACKGROUND
Field
[0002] The present disclosure relates to a traffic light
information providing system and a traffic light information
providing method as well as a server used therefor and more
particularly to a technique of providing information on change in
color of a traffic light to a vehicle.
Description of the Background Art
[0003] A green wave drive support system has been known that aims
at reduction in energy loss and CO2 emission by suppressing
acceleration and deceleration involved with stop at the red light
by giving a notification about a speed at which a vehicle can pass
a next intersection on the green light during running.
[0004] International Publication WO2014/115309 discloses a movement
assistance system configured to present a remaining lighting time
of a traffic light based on traffic light information obtained by
using a post service of a social networking service (SNS).
SUMMARY
[0005] In a conventionally available drive support system based on
road-vehicle communication, a road-side device for transmitting
traffic light information to a vehicle should be provided at each
intersection where a traffic light is provided. Therefore,
construction of a system has highly been costly and it has been
difficult to realize the system.
[0006] In the system disclosed in International Publication
WO2014/115309, traffic light information is obtained by using a
post service of an SNS. Therefore, a road-side device to be
provided around an intersection as above is not necessary and
provision of movement assistance which is highly accurate by using
latest information posted to an SNS server can be expected.
[0007] The system disclosed in International Publication
WO2014/115309, however, requires information on a picked-up image
of a traffic light posted to an SNS site. Therefore, when nobody
posts information on a picked-up image, a period of change in color
of a traffic light cannot be specified.
[0008] The present disclosure was made to solve such problems, and
an object thereof is to provide a traffic light information
providing system and a traffic light information providing method
capable of providing drive support by specifying a period of change
of a traffic light without introducing a new device.
[0009] A traffic light information providing system according to
the present disclosure provides information on change in color of a
traffic light to a vehicle. The traffic light information providing
system includes a vehicle and a server configured to communicate
with the vehicle. The vehicle is configured to transmit to the
server, vehicle data including time information and position
information of the vehicle when the vehicle resumes running from a
state of stop at an intersection. The server is configured to (a)
operate and store a period of change from a red light to a green
light of a traffic light provided at the intersection based on the
vehicle data and (b) transmit information indicating timing of
change of the traffic light to the green light based on the stored
period of change, to a vehicle which approaches the
intersection.
[0010] The vehicle is configured to transmit the vehicle data to
the server when a vehicle speed exceeds a threshold value from the
state of stop at the red light at the intersection.
[0011] According to the traffic light information providing system
in the present disclosure, the server operates a period of change
of a traffic light provided at an intersection based on vehicle
data including time information and position information of a
vehicle at the time when the vehicle resumes running from a state
of stop at the intersection. Though timing of transmission of the
vehicle data from the vehicle is determined based on position
information of the vehicle and a vehicle speed, such information
can be obtained from devices generally provided in vehicles.
Vehicle data to be transmitted is also configured with information
from devices generally provided in vehicles. Therefore, the traffic
light information providing system according to the present
disclosure can specify a period of change of a traffic light
without introducing a new device. Cost for constructing a system
can thus be suppressed.
[0012] The vehicle is configured to transmit the vehicle data to
the server when the vehicle resumes running from a state that the
vehicle is at the head of vehicles which stop at the
intersection.
[0013] Timing of resumption of running by a vehicle at the head of
vehicles which stop at the red light at an intersection is not
affected by a preceding vehicle. Therefore, a time lag between
timing of change of a traffic light from the red light to the green
light and timing of resumption of running of the vehicle at the
head is less than a time lag of other vehicles. Therefore, accuracy
in operation of the period of change can be enhanced by using
vehicle data at the timing of resumption of running of the vehicle
located at the head of vehicles which stop at an intersection.
[0014] The server is configured to identify a traffic light based
on the position information and to operate the period of change of
the traffic light based on the time information accumulated for
each identified traffic light.
[0015] According to such a configuration, a period of change can
statistically be estimated in consideration of accumulated past
data. Accuracy in operation of the period of change can thus be
enhanced.
[0016] The server is configured to operate a predicted time of
change of the traffic light to the green light based on latest time
information on change of the traffic light to the green light and
the operated period of change, and transmit the predicted time to
the vehicle which approaches the intersection.
[0017] According to such a configuration, subsequent time of change
to the green light can be predicted in consideration of latest time
of change to the green light. Accuracy in subsequent timing of
change to the green light of which notification should be given to
a user can be enhanced.
[0018] The server is configured to operate and store the period of
change of the identified traffic light in accordance with at least
any one category of a month, a day of a week, and a time of a
day.
[0019] According to such a configuration, by finely setting a time
segment for each traffic light, accuracy in operation of a period
of change can be enhanced and accuracy in predicted time of change
of the traffic light can be enhanced.
[0020] A traffic light information providing method according to
another aspect of the present disclosure is a method of providing
information on change in color of a traffic light in a system
including a vehicle and a server configured to communicate with the
vehicle. The traffic light information providing method includes
(a) transmitting to the server, vehicle data including time
information and position information of the vehicle when the
vehicle resumes running from a state of stop at an intersection,
(b) operating and storing a period of change from a red light to a
green light of a traffic light provided at the intersection based
on the vehicle data, and (c) transmitting information indicating
timing of change of the traffic light to the green light based on
the stored period of change, to a vehicle which approaches the
intersection.
[0021] A server according to yet another aspect of the present
disclosure is included in a traffic light information providing
system for providing information on change in color of a traffic
light to a vehicle. The server is configured to communicate with a
vehicle. The server is configured to (a) receive vehicle data
including time information and position information of the vehicle
when the vehicle resumes running from a state of stop at an
intersection, (b) operate and store a period of change from a red
light to a green light of a traffic light provided at the
intersection based on the vehicle data, and (c) transmit
information indicating timing of change of the traffic light to the
green light based on the stored period of change, to a vehicle
which approaches the intersection.
[0022] According to the present disclosure, a traffic light
information providing system can specify a period of change of a
traffic light based on position information of a vehicle obtained
by using GPS and vehicle speed information obtained from a vehicle
speed sensor. Therefore, a period of change of a traffic light can
be specified without introducing a new device. Cost for
constructing a system can thus be suppressed.
[0023] The foregoing and other objects, features, aspects and
advantages of the present disclosure will become more apparent from
the following detailed description of the present disclosure when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a diagram schematically showing an overall
configuration of a traffic light information providing system
according to the present embodiment.
[0025] FIG. 2 is a block diagram for illustrating details of a
vehicle and a server in FIG. 1.
[0026] FIG. 3 is a flowchart for illustrating processing for
transmitting vehicle data from a vehicle to the server.
[0027] FIG. 4 is a diagram showing exemplary vehicle data
transmitted from the vehicle to the server in FIG. 3.
[0028] FIG. 5 is a flowchart for illustrating processing for
operating a period of change of a traffic light performed in the
server.
[0029] FIG. 6 is a first diagram for illustrating an approach to
operate a period of change of a traffic light.
[0030] FIG. 7 is a second diagram for illustrating an approach to
operate a period of change of a traffic light.
[0031] FIG. 8 is a diagram showing exemplary period-of-change data
generated in FIG. 5.
[0032] FIG. 9 is a flowchart for illustrating processing for
operating a predicted time of change of a traffic light performed
in the server.
[0033] FIG. 10 is a diagram showing exemplary data on a predicted
time of change of a traffic light transmitted from the server to a
vehicle.
[0034] FIG. 11 is a diagram showing exemplary representation on a
navigation device of a vehicle.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] An embodiment of the present disclosure will be described in
detail below with reference to the drawings. The same or
corresponding elements in the drawings have the same reference
characters allotted and description thereof will not be
repeated.
[0036] FIG. 1 is a diagram schematically showing an overall
configuration of a traffic light information providing system 10
according to the present embodiment. Referring to FIG. 1, traffic
light information providing system 10 includes a plurality of
vehicles 100 (which are also simply referred to as a "vehicle"
below) and a server 200 which can communicate with vehicle 100.
Vehicle 100 and server 200 are configured to transmit and receive
information to and from each other through a communication network
300 such as the Internet or telephone lines. Vehicle 100 and server
200 may directly communicate with each other, not via communication
network 300.
[0037] In traffic light information providing system 10, server 200
operates a period of change of a color of a traffic light provided
at each intersection based on information obtained from vehicle 100
and transmits to vehicle 100, time information at which the traffic
light will change to the green light next time. In vehicle 100,
time information transmitted from server 200 is given to a driver
so that drive support is provided to decrease deceleration for the
red light or avoid stop at the red light. Thus, it can be made to
contribute to reduction in energy loss and CO2 emission involved
with deceleration and stop can be made.
[0038] (Configuration of Vehicle and Server)
[0039] FIG. 2 is a block diagram for illustrating details of
vehicle 100 and server 200 in FIG. 1. Referring to FIG. 2, vehicle
100 includes a camera 110, a speed detector 120, a control device
130, a storage 140, a communication unit 150, and a navigation
device 160. These devices are configured to transmit and receive
information to and from one another through a data bus 170.
[0040] Communication unit 150 is a communication interface between
vehicle 100 and communication network 300. Vehicle 100 transmits
and receives information to and from server 200 through
communication unit 150.
[0041] Camera 110 is implemented, for example, by a charge coupled
device (CCD) camera and attached to a position at which the camera
can shoot video forward of vehicle 100. Camera 110 is mounted, for
example, as a part of a dashboard camera for recording video at the
time when vehicle 100 encounters an accident. The video shot with
camera 110 is transmitted to server 200 through communication unit
150.
[0042] Speed detector 120 detects a running speed of vehicle 100.
Speed detector 120 may be a rotation sensor for detecting a
rotation speed of wheels or a speed sensor which uses laser
beams.
[0043] Navigation device 160 includes a display 162, an audio
output portion 164, and a position detector 166. Display 162 is
implemented, for example, by a liquid crystal panel and shows a
position of vehicle 100 on map information stored in storage 140 or
shows guidance on a route to a destination. When a touch panel
function is provided to display 162, display 162 also functions as
an input unit which accepts an operation by a user. Audio output
portion 164 outputs through voice and sound, guidance on a route,
an alarm at the time of occurrence of an abnormal condition, or
advice to a user during running.
[0044] Position detector 166 obtains absolute position information
of vehicle 100 by using a global positioning system (GPS).
Navigation device 160 shows a position of vehicle 100 on display
162 based on the obtained position information. Position detector
166 outputs obtained position information to server 200.
[0045] Control device 130 includes a central processing unit (CPU),
a storage device such as a memory, and an input and output buffer,
none of which is shown, and controls entire vehicle 100 in a
centralized manner. Control device 130 includes a vehicle data
generator 132 and a display data generator 134.
[0046] Vehicle data generator 132 generates data on timing of
change in color of a traffic light provided at an intersection
(which is also referred to as "vehicle data" below) and transmits
the vehicle data to server 200. As will be described later, server
200 operates a period of change of the traffic light from the red
light to the green light based on the vehicle data from vehicle
100, and predicts time of change of the traffic light to the green
light based on the period of change.
[0047] Display data generator 134 receives information on time of
change to the green light predicted by server 200 and generates
data for representation on display 162 of navigation device
160.
[0048] Server 200 includes a controller 210, a storage 220, and a
communication unit 230. Controller 210 includes a period-of-change
operation unit 212 and a time-of-change predictor 214.
[0049] Communication unit 230 is a communication interface between
server 200 and communication network 300. Server 200 transmits and
receives information to and from vehicle 100 through communication
unit 230.
[0050] Controller 210 includes a central processing unit (CPU), a
storage device such as a memory, and an input and output buffer,
none of which is shown. Controller 210 includes period-of-change
operation unit 212 and time-of-change predictor 214.
Period-of-change operation unit 212 operates a period of change of
a traffic light provided at an intersection from the red light to
the green light based on information included in the vehicle data
transmitted from vehicle 100. The operated period of change is
stored in storage 220 for each traffic light.
[0051] When approach of vehicle 100 to an intersection is sensed,
time-of-change predictor 214 predicts time of change to the green
light of the traffic light provided at the intersection based on
data on the period of change stored in storage 220 and transmits
the predicted time to vehicle 100.
[0052] Vehicle 100 shows the predicted time obtained from server
200 on display 162 of navigation device 160 and notifies a user of
the predicted time. Alternatively, vehicle 100 may give a
notification about a recommended speed at which the vehicle will be
able to pass the intersection on the green light at the time of
arrival at the intersection based on the obtained predicted time
and a position of vehicle 100. Deceleration or stop of vehicle 100
by a user for the red light of the traffic light at the time of
arrival of vehicle 100 at the intersection can thus be decreased so
that energy loss and CO2 emission can be reduced.
[0053] (Description of Contents of Control)
[0054] In such a system capable of what is called green wave drive
support, information on a traffic light at each intersection should
be collected. In a conventionally available system, a road-side
device for transmitting information on a traffic light to a vehicle
should be provided at each intersection provided with a traffic
light. Therefore, cost for constructing infrastructures for
construction of the system has been high and it has been difficult
to realize the system.
[0055] In the present embodiment, an approach to operate a period
of change of a traffic light at each intersection from the red
light to the green light based on position information and vehicle
speed information of a vehicle which have conventionally been used
in vehicles, and to predict a future time of change to the green
light based on the operated period of change is adopted.
[0056] Specifically, when vehicle data generator 132 of vehicle 100
detects resumption of running from a state of stop of vehicle 100
at an intersection (that is, a vehicle speed has attained to a
prescribed threshold value .alpha. km/h (>0)) based on map
information and position information of vehicle 100 obtained by
navigation device 160 and vehicle speed information from speed
detector 120, time information and position information of vehicle
100 at that time are transmitted to server 200.
[0057] A state of stop of vehicle 100 at an intersection is
generally considered as being attributed to the red traffic light
at the intersection. In many cases, running is resumed from that
state at timing of change from the red light to the green light of
the traffic light. Therefore, in the present embodiment, timing of
resumption of running from the state of stop of vehicle 100 at an
intersection is regarded as timing of change of the traffic light
at the intersection from the red light to the green light, so that
timing of change in color of the traffic light can be detected with
an existing device without performing complicate processing such as
image analysis.
[0058] It is preferable to transmit vehicle data, when vehicle
stops at the head of a plurality of vehicles which stop as waiting
for a traffic light at an intersection (that is, a position closest
to the intersection). If another vehicle stops ahead of vehicle
100, vehicle 100 is unable to immediately start running even though
the traffic light changes from the red light to the green light,
and there is a time lag between timing of actual change of the
traffic light and timing of start of vehicle 100.
[0059] Processing performed in vehicle 100 and server 200 in
traffic light information providing system 10 in the present
embodiment will be described below in further detail.
[0060] FIG. 3 is a flowchart for illustrating processing for
transmitting vehicle data from vehicle 100 to server 200.
Flowcharts shown in FIG. 3 and FIGS. 5 and 9 which will be
described later are executed as a result of calling of a program
stored in control device 130 of vehicle 100 or controller 210 of
server 200 from a main routine every prescribed period or when a
prescribed condition is satisfied. Alternatively, some or all of
steps in the flowcharts can also be processed by dedicated hardware
(electronic circuits).
[0061] Referring to FIG. 3, vehicle 100 determines in step (which
is abbreviated as S below) 100, whether or not vehicle 100 stops at
the head of vehicles which stop at an intersection. Such
determination can be made, for example, based on a distance from
the intersection to vehicle 100. Alternatively, absence of a
vehicle ahead of vehicle 100 may be detected based on video from
camera 110 or information from a not-shown ultrasonic sensor.
[0062] When vehicle 100 is not at the head of vehicles (NO in
S100), subsequent processing is skipped and the process ends. When
vehicle 100 is at the head of vehicles (YES in S100), the process
proceeds to S110 and vehicle 100 determines whether or not a
vehicle speed has increased to a prescribed threshold value
(.alpha. km/h) from a state of stop (=0 km/h), that is, running has
been resumed from the state of stop. When a vehicle speed is lower
than the threshold value (NO in S110), vehicle 100 remains stopped
or runs at a low speed as creeping and running has not yet been
resumed. Therefore, processing in step S120 is skipped and the
process ends.
[0063] When the vehicle speed is higher than the threshold value
and running has been resumed (YES in S110), vehicle 100 determines
that the traffic light has changed from the red light to the green
light and the process proceeds to S120. In S120, vehicle 100
transmits vehicle data including time and position information of
the vehicle at that time to server 200.
[0064] FIG. 4 is a diagram showing exemplary vehicle data obtained
by server 200. Referring to FIG. 4, the vehicle data includes a
position of a vehicle (vehicle position), time and day, and a day
of a week. In a coordinate (X, Y, Z) shown in the field of vehicle
position, X represents a longitude, Y represents a latitude, and Z
represents an altitude. A standing time of vehicle 100 at an
intersection and video from camera 110 while the vehicle remains
stopped may also be transmitted together as the vehicle data.
[0065] An example in which data is not transmitted to server 200
when vehicle 100 is not a vehicle at the head is shown for step
S100. When vehicle 100 is not a vehicle at the head, however, time
of resumption of running may be corrected in accordance with a
distance from an intersection to a stop position and then vehicle
data may be transmitted to server 200.
[0066] Processing for operating a period of change of a traffic
light performed in server 200 will now be described with reference
to FIGS. 5 to 8. FIG. 5 is a flowchart of processing for operating
a period of change performed in server 200.
[0067] Referring to FIG. 5, server 200 determines in S200 whether
or not it has received vehicle data from vehicle 100. When the
server has not received vehicle data (NO in S200), subsequent
processing is skipped and the process ends.
[0068] When the vehicle data has been received (YES in S200), the
process proceeds to S210 and server 200 obtains position
information from the received vehicle data and specifies an
intersection where vehicle 100 has stopped. Storage 220 of server
200 stores in advance information representing correspondence
between an intersection and a traffic light provided at the
intersection. Server 200 obtains an identifier of the traffic light
provided at the intersection where vehicle 100 has stopped (which
is also referred to as a "traffic light ID" below) based on this
information.
[0069] In step S220, server 220 operates a period of change of the
traffic light to the green light based on the time information
obtained from vehicle 100 and most recent time information stored
in storage 220 for the specified traffic light ID.
[0070] Server 200 generates data in which latest time information
obtained from vehicle 100 and past time information stored in
storage 220 are chronologically arranged (FIG. 6) and operates a
difference between adjacent times (that is, a period of change from
previous change to the green light to present change to the green
light). Timing to start running of a vehicle by a user may vary
depending on circumstances of the surroundings or user's attention.
Therefore, the period found based on the difference in time as
above may also vary. Therefore, server 200 operates a period of
change of the traffic light in a statistic approach based on the
operated period. Specifically, server 200 generates a distribution
(a histogram) of operated periods (FIG. 7) and operates a period of
change T of the traffic light based, for example, on an average
value or a median value (a median) in the histogram.
[0071] Server 200 stores in S230, the operated period of change for
each traffic light ID as a map divided into months, days of a week,
and times of a day as in an example shown in FIG. 8. By thus
storing the period of change for each category, time of change of
the traffic light of which period of change is set differently for
each season, each day of a week, and each time of a day can also
appropriately be predicted. The category for storage of periods of
change is not limited to those shown in FIG. 8 and another category
may be adopted.
[0072] A configuration for predicting time of change of a traffic
light which a vehicle will reach in the near future based on the
stored period of change and notifying the vehicle of the predicted
next time of change (the predicted time of change) will now be
described.
[0073] FIG. 9 is a flowchart for illustrating processing for
operating a predicted time of change of a traffic light performed
in server 200.
[0074] Referring to FIG. 9, server 200 determines in S300 whether
or not it has received request information on a predicted time of
change of a traffic light from vehicle 100. The request information
is transmitted from vehicle 100 to server 200 when vehicle 100
approaches an intersection on a route. This request information
includes information for identifying vehicle 100, position
information of an intersection, and information on a predicted time
at which vehicle 100 will reach the intersection. The request
information is generated by vehicle data generator 132 based on
data obtained from navigation device 160 of vehicle 100.
[0075] When no request information has been received (NO in S300),
subsequent processing is skipped and the process ends. When the
request information has been received (YES in S300), the process
proceeds to S310 and server 200 obtains a traffic light ID of a
traffic light provided at an intersection from storage 220 based on
position information of the intersection included in the request
information.
[0076] Server 200 obtains in S320, period-of-change data Tr of the
traffic light with the obtained traffic light ID by referring to
the map stored in storage 220 (FIG. 8). Server 200 obtains latest
data t0 on time of change of the traffic light to the green light
from storage 220 (S330). Server 200 operates a predicted time of
change after the current time point (t0+n.times.Tr) based on
obtained period-of-change data Tr and latest time of change t0
(S340), where n represents an integer not smaller than 1. n=1
represents a next predicted time of change and n=2 represents a
predicted time of change after the next.
[0077] Thereafter, server 200 transmits in S350 to vehicle 100,
information on the predicted time of change in connection with the
traffic light ID as shown in FIG. 10.
[0078] In vehicle 100, information on the predicted time of change
transmitted from server 200 is shown on display 162 of navigation
device 160. FIG. 11 is a diagram showing exemplary representation
on display 162 of navigation device 160. Referring to FIG. 11,
display 162 shows a predicted time when a traffic light which
vehicle 100 approaches will turn green next time and a predicted
time when vehicle 100 will reach the intersection.
[0079] For example, in FIG. 11, a predicted time when the traffic
light will turn to green next time is twelve ten and zero second
and a predicted time when vehicle 100 will reach an intersection
where the traffic light is provided is twelve nine and thirty
seconds. In this example, with a current vehicle speed being
maintained, the traffic light has not yet turned to green at a time
point when the vehicle reaches the intersection and the vehicle is
predicted to stop at the red light for approximately thirty
seconds. In this case, for example, by slightly decelerating
vehicle 100 and delaying time to reach the intersection, a user can
pass the intersection on the green light.
[0080] A recommended vehicle speed may also be shown on display 162
for passing the intersection on the green light at the time when
the vehicle reaches the intersection.
[0081] As set forth above, in a signal information providing system
in the present embodiment, timing of resumption of running from a
state of stop of a vehicle at an intersection is regarded as timing
of change of a traffic light to the green light and information on
the vehicle at that time is collected by the server. A period of
change of each traffic light is thus specified. Information
transmitted from a vehicle can be obtained with a position
detection function provided in the navigation device and resumption
of running can be obtained with a speed detector such as a vehicle
speed sensor. Thus, the signal information providing system
according to the present embodiment can use information from
devices conventionally mounted on vehicles to specify a period of
change of a traffic light without introducing a new apparatus and
hence the system can be constructed with low cost.
[0082] Though an embodiment of the present disclosure has been
described, it should be understood that the embodiment disclosed
herein is illustrative and non-restrictive in every respect. The
scope of the present disclosure is defined by the terms of the
claims and is intended to include any modifications within the
scope and meaning equivalent to the terms of the claims.
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